Evaluation of magnetic resonance imaging issues for a wirelessly powered lead used for epidural, spinal cord stimulation.

OBJECTIVE: The objective of this investigation was to evaluate magnetic resonance imaging (MRI) issues (magnetic field interactions, MRI-related heating, and artifacts) for a wirelessly powered lead used for spinal cord stimulation (SCS). MATERIALS AND METHODS: A newly developed, wirelessly powered lead (Freedom-4, Stimwave Technologies Inc., Scottsdale, AZ, USA) underwent evaluation for magnetic field interactions (translational attraction and torque) at 3 Tesla, MRI-related heating at 1.5 Tesla/64 MHz and 3 Tesla/128 MHz, and artifacts at 3 Tesla using standardized techniques. MRI-related heating tests were conducted by placing the lead in a gelled-saline-filled phantom and performing MRI procedures using relatively high levels of radiofrequency energy. Artifacts were characterized using T1-weighted, spin echo (SE), and gradient echo (GRE) pulse sequences. RESULTS: The lead exhibited minor magnetic field interactions (2 degree deflection angle and no torque). Heating was not substantial under 1.5 Tesla/64 MHz (highest temperature change, 2.3°C) and 3 Tesla/128 MHz (highest temperature change, 2.2°C) MRI conditions. Artifacts were moderate in size relative to the size and shape of the lead. CONCLUSIONS: These findings demonstrated that it is acceptable for a patient with this wirelessly powered lead used for SCS to undergo MRI under the conditions utilized in this investigation and according to other necessary guidelines. Artifacts seen on magnetic resonance images may pose possible problems if the area of interest is in the same area or close to this lead.

Evaluation of MR safety for a new liquid embolic device.

BACKGROUND: As an alternative to conventional treatments, a new liquid embolic device (Neucrylate) may be used to treat aneurysms or arteriovenous malformation (AVMs). Because this device contains metal for opacification, an investigation was performed to evaluate MRI issues for this liquid embolic device. METHODS: The liquid embolic device was evaluated for magnetic field interactions (translational attraction and torque) at 3 T, MRI-related heating at 1.5 T/64 MHz and 3 T/128 MHz and artifacts at 3 T using standardized techniques. In each case, MRI-related heating was assessed with the liquid embolic device in a gelled saline-filled phantom and MRI was performed using relatively high levels of radiofrequency energy. Artifacts were characterized using T1-weighted spin echo and gradient echo pulse sequences. Additionally, conductivity (ie, electrical resistance) measurements were recorded. RESULTS: The liquid embolic device exhibited no magnetic field interactions. Heating was at the same level as background temperature rises (ie, the temperatures recorded without the liquid embolic device present in the phantom) under 1.5 T/64 MHz (highest temperature change 1.4 °C) and 3 T/128 MHz (highest temperature change 1.8 °C) MRI conditions. Artifacts were small in relation to the size and shape of the liquid embolic device. The device was found to pose no risks with regard to the conductivity of the material. CONCLUSIONS: These findings demonstrate that it is acceptable for a patient with this new liquid embolic device to undergo MRI at ≤3 T. Notably, the associated artifacts are unlikely to create issues for diagnostic MRI examinations.